Vinegar comes in many varieties and is made by fermenting ethanol into aceyic acid. This starts with a plant base (grapes, apples, barley) which is then fermented or distilled into wine, beer or malt, and then further fermented to yield a vinegar. Vinegars can also be infused with fruits and herbs which enhance their flavor profiles. The only animal based exception I found is honey vinegar, which would not be vegan as honey is used as the flavoring agent. However, honey vinegar is fairly rare, at least here in the US and will likely be labeled specifically.

I have never heard of or subsequently read about any vinegar that comes from whey.

When researching whether or not isinglass is used in filtering, it seems to me that while that is a method that can be used, it is not very popular. I took the liberty of contacting Heinz, a major manufacturer of many vinegars to see if they used isinglass. They did not:

June 28, 2011
Dear Melissa,
Thank you for visiting our web site.
Heinz vinegar is not filtered through isinglass. It is considered suitable for vegetarians.
Thanks again for contacting us. We appreciate your interest.
Heinz Consumer Resource CenterHeinzconsumeraffairs@us.hjheinz.com

We certainly can’t speak for every vinegar manufacturer out there, but I feel confident with vinegar’s vegan status.

My underestanding is that vinegar eels (Turbatrix aceti) grow on pretty much all vinegar, and are killed and filtered out before bottling for commercial distribution. These are not microorganisms, they are visible to the naked eye.

I know this is a pretty old post, but just adding my two cents. I’m from Germany and the vegan community over here pretty much came to the conclusion (through research and contacting tons of different manufacturers) that most vinegars are in fact non vegan. Except for basic white vinegar, which is made from simple alcohol.Most others are made from wines or beer or fruit juices and thoses are usually cleared up “to please the eye” before being sold or made into vinegar. That can be achieved by either using isinglass, gelatin or a mechanical process, So one really has to ask the manufacturers every single time.